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Butt welds with different material thickness

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  • Butt welds with different material thickness

    In one piece I build, I make what ends up being a butt weld where 2 x 2 x 11g square tubing meets up with 1/2" x 2" flat bar. With the material being drastically different thicknesses, what recommendations do y'all have as far as settings?
    My setting were as follows:

    Machine: Miller 350P
    process: pulse
    wire: .035
    Gas" 90/10 @ 35cfh
    base setting 300
    arc length 50 ( factory)
    arc control 0 (factory is 25)
    Direction of travel - Push

    I deburred the edge of the tubing but did not bevel. Fla bar was not beveled either. It doesn't make sense to me to bevel too much as the tubing isnt extremely thick. If I bevel the 1/2" there ends up being a gap unless I only slightly bevel to match up with the tubing.

    For reference, the settings for 1/8" is 250 and 1/2" is 650 on the chart.

    By turning the arc control to 0, I was looking to get a flatter bead.

    Finished bead gets minimal finish grinding with a flap wheel followed by wire wheel.

    Desired result is 1) a sound bead. 2) a good looking bead that requires minimal clean up

    Thanks in advance for replies

    Scott
    Attached Files

  • #2
    I don't remember the settings I used and don't have gages on my machine but I welded this Wednesday, it's the top of my welding table I just built. Its 14 gauge 2" X 2" square tube to 1/2" plate. I'm using a MM211 with 75/25 gas and .030 wire. I think it was set at about 5.5 with a wire speed of about 65 on the dials but have changed them since so unsure. just sanded to debur, no bevels. I don't have a pic with me but also have a place on it with 11 gauge flat bar welded to the 1/2" plate will try to check tomorrow.Name:  df04b6d34a2033077eee2dec1067bed0.jpg
Views: 1
Size:  69.6 KB

    Comment


    • #3
      1. Not what I call a butt weld. Filet.

      2. You're making this a lot more complicated than it is. I know you got a great machine with a lot of bells and whistles, but, like fast cars, just because it will run 160 MPH doesn't mean you drive around town at that speed.

      The weld I see in your photo could easily be done (with proper technique) using short arc and would look a lot better. The weld only has to be as strong as the weakest component, in this case the 11 ga. square tubing.

      I'd suggest spending more time on developing proper technique and less time on fancy pulse settings on your machine.

      Not trying to put you down but that, to me, is an ugly weld that I wouldn't be happy showing as representative of my work.

      When you get to something that "requires" pulsed spray, post up some photos and we'll give some recommendations to get you headed in the right direction.

      Comment


      • #4
        I do things on a regular basis very similar with what you pictured ,,,, only with 1/4" tube. Normally I bevel the tube. In your case, you could put a small bevel, on the outside edges of the flat, and running with correct heat and correct technique, end up with a very flat correctly-sized weld as strong as is necessary, given the size of your tube, and much more attractive. No grinding needed.

        Comment


        • #5
          Fillet Welds

          S & P: Sundown's right on his mark. Fillet welds are always based on the thinner of the two materials. Adding more filler does nothing for the strength of the weld, it only wastes consumables and time.

          Here's a formula you can jot down for fillets, where the strength of the weld matches the plate.

          Full Strength Weld: (w= 3/4 t) Material less than 1/4" = 1/8 w

          You would only need a 1/8" fillet to weld the square tubing to the flat bar.

          Fillet welds are measured by the leg size of the largest right triangle that may be inscribed within the cross-sectional area. The throat (a better index to strength) is the shortest distance between the root of the joint and the face of the diagrammatical weld.

          Fillet weld gauges are a handy tool to keep in your tool box. I've got a set from Harris (#MWFG) and measures both concave and convex fillets.

          Takes a lot of guess work out of fabricating.

          I probably would have used a 7018, and made some real pretty fillets, but, that's me

          Just set your MIG for short-arc, for 11 ga (1/8") material and squeeze the trigger

          Dave
          Last edited by davedarragh; 02-19-2010, 12:03 PM.

          Comment


          • #6
            How i'm seeing it, this is considered a square groved butt weld.I dont see how it can be considered a fillet weld when both pieces to be joined are flush at the top. I know the inside is a fillet but the other 3 sides are flush.
            Putting a slight gap between the two pieces would give a complete fusion weld.It also allows less stress on the weld due to contraction.
            Last edited by fabricator; 02-19-2010, 06:44 PM.

            Comment


            • #7
              Im gonna get me one of those 350Ps one of these days.

              But until then Im stuck doing things the old way. Personally Id set the machine where it was just a tad cold for the 1/2 inch flatbar, then Id run a J pattern keeping the long part of the J on the 1/2 inch flatbar, only dipping into the 11-GA tube to stitch it up. Back up on the thick part move forward dip back into the thin part. Repeat as many times as necessary!
              Attached Files

              Comment


              • #8
                Originally posted by SundownIII View Post
                1. Not what I call a butt weld. Filet. I guess my understanding of a butt and filet weld are wrong, I will keep reading The procedure handbook of arc welding

                2. You're making this a lot more complicated than it is. I know you got a great machine with a lot of bells and whistles, but, like fast cars, just because it will run 160 MPH doesn't mean you drive around town at that speed. This was the first time I adjusted the "bells and whistles". In other posts, I have seen, the OP wants weld advice but doesn't give any info on settings or pictures. Y'alls time is valuable so I put down everything I had to eliminate guesswork.

                The weld I see in your photo could easily be done (with proper technique) using short arc and would look a lot better. The weld only has to be as strong as the weakest component, in this case the 11 ga. square tubing.

                I'd suggest spending more time on developing proper technique and less time on fancy pulse settings on your machine.Any advice you can give to this end is greatly appreciated

                Not trying to put you down but that, to me, is an ugly weld that I wouldn't be happy showing as representative of my work.A) what do you see that makes it ugly and B) What do you suggest to make it better?

                When you get to something that "requires" pulsed spray, post up some photos and we'll give some recommendations to get you headed in the right direction.What would be a good example where pulsed spray is desirable over short arc?
                I appreciate you taking the time to comment

                Scott

                Comment


                • #9
                  Originally posted by Sonora Iron View Post
                  Im gonna get me one of those 350Ps one of these days.

                  But until then Im stuck doing things the old way. Personally Id set the machine where it was just a tad cold for the 1/2 inch flatbar, then Id run a J pattern keeping the long part of the J on the 1/2 inch flatbar, only dipping into the 11-GA tube to stitch it up. Back up on the thick part move forward dip back into the thin part. Repeat as many times as necessary!
                  As this joint is 2" long, how many J's should I be looking for?

                  Thanks

                  Comment


                  • #10
                    Originally posted by STRENGTH AND POWER View Post
                    As this joint is 2" long, how many J's should I be looking for?

                    Thanks
                    Oh I have no idea.
                    I watch the puddle, and the fusion line. If the thinner material gets so hot that I cannot control the puddle, and the puddle is about to fall in, Ill stop, move to another location. If my production suffers by having to do this too many times, Ill change settings, or technique.
                    Never done it with a Mig welder, (because theyre fantastic at filling gaps) but with SMAW a lot. Knock the flux off another rod and use it as a filler in one hand while welding with the other, (same technique as O/A or Tig welding).

                    Comment


                    • #11
                      I think Sonora Iron is old school. I know that because I'm also old school.

                      I learned to weld almost forty years ago using a buzz box and 6011. I would see the roll of dimes look welds and I assumed that meant the weldor was weaving his puddle like a machine. It wasn't until a couple of years later while studying welding in a night class at a junior college (VA Money) that I was exposed to mud rods.

                      The instructor had us gather around and he set up a butt joint using 6013. He struck his arc and just dragged his rod. When he stopped we looked up just in time to see the flux peeling back off the weld exposing the roll of dimes look.

                      "CHEATING SOB'S!!!!" was all I could say.

                      Even when using what I call a mud rod or a mig I still work the weld like I did back then with the 6011. It's not unlike the way you do it with tig or gas welding where you get the puddle and it's like herding cats some days and sheep others.

                      The important thing to remember is the weld is formed when the parent metals get to a liguid state on the surface. The puddle is about the filler material. But what's important is what's happening at the parent metal.

                      The best weld is a forge weld. There the parent material's surface is brought to a liquid state, a flux is applied, and pressure is applied, typically with hammer blows.

                      The beautiful weld is created when the weldor controls the heat and speed. It's all about heat and speed. If you doubt it look at an automatic weld.

                      Comment


                      • #12
                        S&P,

                        Technically what you have there is a corner and a t joint. The t is welded with a fillet weld.

                        Regardless of the naming, the joint is only as strong as the weakest member. In this case the 11ga tube.

                        One of the primary benefits of short arc transfer is the fact that it's a rather low energy, controllable process. You don't have to rush thru your weld.

                        Spray transfer, on the other hand, is a very high energy transfer process designed primarily for welding material over 1/4". An example would be butt welding 3/8" steel. Pulse welding without spray, because you're dealing with a very fluid puddle, is generally to welding in the flat position. Enter pulse spray. The pulsing allows the bead to freeze slightly allowing spray transfer in other than the flat position. An example here would be a vertical up fillet in 3/8" steel.

                        Short response. Spray transfer is a high energy, high deposition, process used for thicker material. Pulsed spray enables the process to be used in other than the flat position.

                        In the case of the project you're doing, short arc has the advantage in that it is slower and allows you to better control the bead. It's more than sufficient to attach 1/8" material to 1/4" material.

                        For that material (using either the 251 or XMT304) I'd start (no pulse) at about 18v with a WFS of about 280 (.035 wire). You may have to back those settings off slightly (they're for 3/16 material) as you try them on some scrap.

                        A consistent push technique will provide the flattest bead. If you're looking for the dimes/ripples, there are several techniques to achieve those.

                        I wasn't trying to put you down in my first post. Just saying there was an easier way to go about the job. The spray transfer process is putting down so much material so fast that it is hard to control on a small job like this. Ugly, may have been too hard a term for the weld I see. Definitely way too much material deposited, and was not consistent from beginning to end. It would require a considerable amount of cleanup/grinding.

                        The 350P is a great machine. Would love to have one (I get by with a 304, digital feeder, and optima pulser). It's capabilities are great. I guess, what I'm saying "in country boy lingo" is you don't go squirrel hunting with a 44 Mag.

                        <3/8" material - short arc
                        >3/8" material - spray
                        >3/8" material, out of position - pulsed spray

                        I'm sure there are guys out there who use spray every day, and can give some tips, however, for the job you're doing, I think you'll get much better results with short arc.

                        Comment


                        • #13
                          Sundown,

                          Thanks for taking the time to break things down into very simple guidelines.

                          Anytime you care to elaborate on achieving the dimes/ripple effect with MIG, I will read and practice thoroughly.

                          I am currently about 1/2 way through a 300cf bottle of 90/10. When's that's gone, based on your suggestions, I am going to get 75/25 for the next round of fun.

                          I started fabrication on my large welding table today where everything is >3/8". Should be a good place to use up the bottle.

                          When choosing between the 251 and 350P, I opted for the 350 to allow room to grow into it's capabilities. It works great and is definitely not the limiting factor in weld appearance

                          Comment


                          • #14
                            S&P,

                            Don't think there is one "CORRECT" way to achieve the ripples. Really comes down to technique and what you feel comfortable with.

                            Some like to use a "C" weave. Some use the "J", etc., etc.

                            Lot will depend on the material and joint type you're dealing with.

                            One excellent discussion of the different techniques can be found in Miller's GMAW Handbook. You can download it from the resources tab above or, even better, order a copy in hard copy. If you order, order the Student Pack. It includes the GMAW Handbook, a GTAW Handbook, and a GMAW-P handbook. Best $25 you'll ever spend in welding.

                            I was very close to upgrading my MM251 to a MM350P, but a "deal I couldn't turn down" came along on an XMT304 and I went that direction. Added a digital wirefeeder (basically the S74DX) and an Optima pulser to get about the same capabilities as the 350P. The 304 requires a little more setup, but has a couple features not avail on the 350P (tig and stick).

                            Bouncing all over>

                            For those edge welds (not the fillet with the T) I would (and I think it's been recommended before) slightly bevel the 2" tube. This will leave a small valley between the two pieces. I'd then use a steady push to fill the void. This will give you the flattest bead requiring a minimum of cleanup. I wouldn't use any fancy oscillations of the tip here. The fillet could be done with the "C" and would give you the ripples.


                            As far as the gas, you may want to stay with the C10. C10 is a more multi use mix than C25. Not sure with the 350P, but with the Optima pulser, many of the spray programs call for the use of C5. If you go with the C25, you're taking away your capability to do spray arc welding (spray, generally requires an argon ratio > 82%).

                            To avoid having to have an assortment of "MIX" bottles, I use the Thermco 8500 mixer. Simple turn of the dial sets the mix. That way I only need to keep on hand a large bottle of Argon and a 50# cylinder of CO2. I use a Smith mixer for mixing Ar/O2 and another Smith mixer for Ar/He (Tig). Really reduces the # of bottles on hand.
                            Last edited by SundownIII; 02-21-2010, 09:36 AM.

                            Comment


                            • #15
                              &quot;The Joint&quot;

                              Scott: Sundown gave you some great advice and recommendations. He really knows his GMAW and GTAW processes. (As does Fusion King)

                              You can narrow down the types of joints to basically these five.

                              Butt, Tee, Corner, Lap, and Edge.

                              The types of welds can be summarized by these six. (both single and double)

                              Fillet (including lap), square, bevel groove, V groove, J groove and U groove.

                              That MM 350 is an oustanding machine. Don't think I was criticizing you when I mentioned I would probably use lo-hi rods, and be done with it.

                              80% of what I do (even small projects), I usually run stick, it's just quicker for me.

                              Keep us posted of your project progress.

                              Dave

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